Screw vane pump



S CREW VANE PUMP Original Filed March 2, 1965 2 Sheets-Sheet 1 FIGLINVENTOR FREDERICK L. PARSONS HIS AT TOR N EYS pt. 27, 1966 F. L.PARSONS P S CREW VANE PUMP Original Filed March 2, 1965 2 $heets-Sheet 2L: Q 22 R ,w\w ggg U N I) k Em \m FIGS.

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(0 x Y e INVENTOR 2 m gt FREDERICK LPARSONS United States Patent3,274,944 SCREW VANE PUMP Frederick L. Parsons, 759 Morningside Road,Ridgevvood, Nd?a Continuation of application Ser. No. 436,534, Mar. 2,1965. This application Sept. 30, 1965, Ser. No. 491,710 14 Claims. ((Zl.1tl313tl) This is a continuation of my United States application SerialNo. 436,534, filed March 2, 1965.

This invention relates to pumps and compressors, and more particularly,to improvements in pumps of the type combining the functions of agyrating rotor and a screw type of pump to increase the eficiency andoutput of such pumps or compressors.

Many attempts have been made in the past to provide a satisfactory pumpof the type having a rotor which gyrates in a pump casing and carries ascrewlike vane in contact with the inner surface of the pump casing toadvance fluid or gases from an inlet to an outlet port by the combinedefforts of the gyrating rotor and screw vane. While, in theory, pumps ofthe type described generally above should operate quietly andefliciently with a minimum of vibration and require a minimum ofmaintenance and servicing, such pumps have not lived up to expectations.Satisfactory pressures are not developed when such pumps are used as gascompressors and their pumping efliciency is quite low when they are usedfor pumping liquids. Moreover, rubbing of the screw-like vane andcontact of the rotor with the cylinder when fitted for proper contacttherewith has caused rapid wear with the result that, in a short time,clearances are left between the rotor and the casing resulting ingreatly reduced pump or compressor efficiency.

A further factor in reducing the efliciency of such pumps is theinability to maintain a satisfactory sealing engagement between thescrew-like vane, the pump cylinder or casing and the rotor because oftolerance problems, thermal expansion, and related factors, particularlywhen the pumps are used for developing relatively high pressures. I havefound that the vane will lose contact with the cylinder and the rotorunder certain conditions allowing the fluid :to escape and back flow.

In accordance with the present invention, pumps of the gy-rating rotorand screw vane type are provided which overcome the disadvantagespointed out above by providing rotor vane structures which maintaintight working engagement with the casing even under high pressures,thereby greatly increasing the pumping efficiency of the pump forliquids and the pressure developed, when the pump is used as a gascompressor, as the case may be.

More particularly, in accordance with the invention, mechanism isprovided whereby the rotor of the pump can be accurately positioned withrespect to the pump casing so as to maintain rolling line or zeroclearance contact therebetween during the operation of the pump withoutmanufacturing the rotor and the casing to close tolerances. Moreover,the screw vane is constructed and arranged so as to oppose loss of itscontact with the wall of the casing, and further the screw vane is soconstructed as to resiliently eliminate clearance with the grooves inthe rotor in which the vane or vanes are received. Moreover, means areprovided in the new pump whereby the discharge pressure of the pump maybe more closely regulated, also pressures developed within the groovesbehind the screw vane can be regulated and controlled, and satisfactorylubrication of the pump can be obtained. In addition, means are providedin the pump whereby pulsa tions developed in fluid passing through thepump can be dissipated to reduce the noise of operation of the pump,thereby rendering it suitable for usage such as, for example, insubmarines where quiet operation is essential.

3 ,274,944 Patented Sept. 27, 1966 For a better understanding of thepresent invention, reference may be had to the accompanying drawings, inwhich: 1

FIGURE 1 is a view in side elevation and partially broken away of atypical pump embodying the present invention;

FIGURES 2 to 7 are views in cross-section of various forms of vaneconstructions used in the pump for minimizing leakage around the vanesduring the operation of the pump; and

FIGURE 8 is a view partially in side elevation and partially in sectionof a coupling for closing and sealing the pressure end of the vane tothe rotor of the pump.

The pump 19 illustrated in FIGURE 1 is of a double screw type by meansof which air or liquid can be supplied from opposite ends of the pump byessentially mirror image pumping elements to a central discharge port 11in the pump casing 12. FIGURE 1 shows only one of the two sections ofthe pump, but it will be understood that the other section of the pumpshown in full lines at the right hand end of FIGURE 1 is essentially thesame except for a reversal of the inclination of the value 13 of thepump.

The pump 10 includes a generally cylindrical casing 12 having heatdissipating vanes extending around it in spaced relation along itslength. The casing includes a cylindrical wall or bore 15. The casing 12may be formed of any suitable type of metal such as steel, aluminum,bronze or the like, as may be required. At each end of the casing 12 issecured a head 16 and 17, the head 16 having a generally annular rimportion 18, a generally disc-like web portion 19, and a concentricallylocated hub portion 2t} for receiving an anti-friction bearing 21 of theball, roller, journal or similar type. One or more openings or passages22 are formed in the head 16 which serve as intake ports for the pump orcompressor.

The head 17 is generally similar to the head 16 except that its rimflange 18 is narrower and the dimensions of the hub therein are ofsomewhat lesser overall length.

Rotatably mounted in the bearing 21 of the hub is a collar 23 which iskeyed to a drive shaft 24 extending axially of the casing 12 and whichcan be coupled to and driven by a suitable power source such as anelectric motor, turbine, internal combustion engine, or the like, as maybe required. At the right hand end of and fixed to or integral with thecollar 23 is an eccentric 25 of generally cylindrical shape having itsaxis offset with respect to the axis of the shaft 24. Rotatably mountedon and concentric with the eccentric 25 by means of bearing 26 is asleeve 27 provided with one or more spring pins 28 extending parallel tothe axis of the eccentric and engaging in the end of a hollow cylinder29 forming a part of the gyrating rotor 30 of the pump. Pins 28 are soarranged as to preload the rotor 30 in respect to its rolling contactwith the casing, by means of a greater throw of the eccentric 25.

The hollow interior of the cylinder 29 provides space for cooling theinterior of the pump.

Fixedly connected to the cylinder 29 is the shell 31 of the rotor whichlikewise is cylindrical in shape and is provided at its opposite endswith generally helical grooves 32 which converge toward the center ofthe rotor 31 and toward the discharge port 11 of the pump or compressor.To conserve Weight, the internal surface of the cylinder 31 is relievedas at the grooves 33 between the internal lands 34 in which the grooves32 are formed. Coolant can be circulated through the grooves 33. Thecylinder 29 and the cylinder 31 may be secured together in any suitableWay, as, for example, by means of the tubular connecting pins 35 whichalso serve another purpose in the pump described hereinafter. Leakagebetween the cylinders 29 and 31 can be minimized by means of suitableO-rings 36 or similar seals. In the structure thus far described, theprovision of the driving spring pins 28 for coupling the rotor 39 to thecollar 27 causes the rotor 30 to be biased toward the casing wall sothat any inaccuracy in the dimension of the internal bore of the pumpcasing and the outer surfaces of the rotor are compensated by the springpressure exerted by the pins 28, thereby assuring essentially leak-tightcontact between the casing 15 and the rotor 30.

Mounted in the helical groove 32 at each end of the rotor 30 is ahelical vane 37 which is mounted in a novel manner and in itself isnovel in structure. While a helical groove 32 and vane 37 of constantpitch are illustrated, the groove and v-ane may be of decreasing pitchtoward the middle of the rotor. Both types of vanes will be referred tohereinafter as helical vanes. The form of the vane shown in FIGURES 1and 2 includes two spaced-apart helical side plates 38 and 39 havingin-turned l-ower flanged edges 40 and 41, the combined widths of whichare slightly less than the width of the helical slot 32 in which theyare received. Between the outer edges of the vane sections 38 and 39 isa screw-like ring 42 which is designed to be slightly larger in diameterthan the inside diameter of the wall 15 'of the pump casing so that thehelical vane portion 42 bears against the wall 15 and maintains sealingor zero clearance engagement therewith. Inwardly of the ring 42 are aseries of small concave-convex springs 43 which tend to force the vanesections 38 and 39 apart and into zero clearance engagement with thewalls 44 and 45 of the groove 32 in the rotor 30. The gap between theinwardly turned flanges 40 and 41 at the inner edges of the vane issea-led and the springs 43 are supported by means of a strip 46 ofresilient, rubbery material, such as rubber, neoprene or the like,depending upon the service conditions under which the pump or compressoris to be used. The strip 46 is compressed somewhat so that it too tendsto urge the Vane sections 38 and 39 apart and to eflectively seal thegap at the inner edge of the vane.

Referring back to FIGURE 1, the end of each vane adjacent the outer endof the rotor 30 is connected to the rotor by means of a constantvelocity Oldham coupling which assures rotary movement of the vane 37with the rotor 30 while nevertheless permitting gyration of the rotoraround the eccentric 25 relative to the casing and the vane. To thatend, the hub 20 of the head 16 is provided with a bearing sleeve 50 onwhich is received rotatably a collar 51 having at one side thereof anoutwardly extending arm 52 which carries a pin 53 extending through theradially extending slot 54 in an intermediate ring 55 and into openingsin the vane side plates 38 and 39 between a pair of the bowed springs 43therein, thereby positioning one end of the "vane 37 in contact with theinner wall 15 of the casing but allowing relative radial movementbetween the rotor 30 and the vane 37. The arm 52 and the collar 51 arecaused to rotate at constant velocity with the rotor by virtue of aspline connection including diametrically spaced splines and grooves 56between the ring 55 and the end of the cylinder 31 of the rotor 30 andright angularly related diametrically spaced spline connections 56a(shown in dotted lines) between the ring 55 and the collar 51. The ring55 being capable of movement in right 'angularly related directionsaccordingly allows the rotor 30 to gyrate relative to the collar 51while causing the collar to rotate with the rotor at a constantvelocity.

Inasmuch as the rotor 30 is mounted eccentrically, counterbalancingmeans is provided to dynamically balance the rotor of the pump,including a counterbalance weight 57 connected by means of screws 53 orthe like to the outer end of the collar 23 at each end of the shaft. Asuitable cover plate 59 encloses the Weight 57 and is secured togetherwith the end plate 16 to the end of the casing 12 by means of threadedstuds 60, bolts or the like.

The head 17 and end plate at the opposite end of the compressor can bethe same as the head 16 and the cover plate 59 but inasmuch as the shaftis supported in the head 17 at a point remote from the drive end, thehead 17 may be made narrower than the head 16. To accommodate thecounterbalance weight, the cover plate 61 may be made deeper and ofsomewhat different shape than the cover plate 59.

With a pump of the type described above and embodying the presentinvention, rotation of the drive shaft 24 causes the rotor to gyrate androll progressively around the wall 15 of the casing and at the same timecauses the vane or vanes 37 therein to rotate relative to the wall 1 5.Such gyration and rotation progressively forces the liquid or gas, asthe case may be, from the inlets at opposite ends of the casing towardthe outlet M. So long as intimate contact is maintained between therotor 30 and the wall 15 of the casing and between the outer edges ofthe vanes and the wall of the casing and between the vanes and the walls44 and 45 of the grooves in the rotor, the pumping or compression ishighly eflicient. In the applicants pump, due to the radial andtransverse expansibility of the vanes 37, the necessary intimate contactis maintained between the vane or vanes, the casing and the rotor. Also,because of the resilient action of the pins 28 mounting the rotor 30,intimate contact is maintained between the rotor and the wall 15. Suchcontact, of course, results in wear. To that end, suitable lubricationfor the pump must be supplied. In a gas compressor, a lubricant, such asoil, can be introduced at any selected point along the length of thecasing, and, for example, oil may be atomized or sprayed in minutequantities by means of a spray nozzle 65 into the intake ports where itis carried by the air into contact with the moving parts of the pump.Any oil or lubricant carried out of the discharge port 11 may be removedfrom the air by a suitable oil separator.

When pumping liquids, a lubricant ordinarily is not required and so thelubricating system may be omitted in such pum-ps except for bearings 21and 26 which can be of the grease sealed type requiring only infrequentservicing.

To further minimize leakage in the system such as would be caused byback flow of fluid along the groove 32 radially inwardly of the vane 37,the free inner or pressure end of the vane may be sealed from the rotorin the manner shown in FIGURE 8. In .and spanning the groove 32 in therotor is a fixed filler plate 66 which is adapted to receive thesemi-cylindrical head 67 of an expansible element 68. Anothercylindrical head 69 is received in a complementa'l recess or notch inthe free end of the vane 37 and has a tongue 70 which is slidablyreceived in the bifurcated arm 71 extending from the head 67. The tongue70 and the bifurcated arm span the groove 32, and if necessary may beprovided with edge seals to prevent or reduce leakage past them.

Any fluid or liquid which is pumped along the bottom of the groove bythe relative movements of the rotor and the vane may be bled into theinterior of the cylinder 29 by means of a bleeder valve 72, that may beset to maintain any desired pressure in groove 32 as shown in FIGURE 1.

Also, in the event that regulated pressures are desired in the pump, ableeder valve 73 which can be preset to a desired pressure may bemounted in a radial bore 74 in the cylinder portion 31 in communicationwith the tubular coupling 35, to allow excess pressure to be vented intothe cylinder 29 and thus mingled with the fluid entering through theintake ports 22. In a liquid pump, the valve 73 may be present to aboutthe pressure to be delivered to the pressure port 11 to prevent pressurefluctuations and resulting noise.

It should be noted that the interior of the rotor is in communicationwith the intake port at each end and thus the fluid flow through theinterior of the rotor also is induced by the operation of the pump sothat effective cooling of the compressor is afforded. Coolant can becirculated through a coil (not shown) in the relieved portions 33 of therotor if necessary.

It will be apparent from the foregoing that the apparatus disclosed inFIGURES l, 2 and 8 overcomes the ditficulties encountered in maintainingeflicient operation and developing high pressures in the gyrating rotorand screw vane type of pumps proposed heretofore. Moreover, by thearrangement of the elements in the pump in the manner described, easyaccess may be had to any part of the pump for inspection or the likemerely by removing one or both of the cover plates and the correspondingheads.

It will be understood that other features may be incorporated in thepump or compressor and modifications made therein. Thus, as shown inFIGURE 1, pulsation which might develop in the pump by the discharge ofgas or liquid through the discharge port can be dampened by providing inthe portion of the rotor 30 adjacent the outlet port, a cavity 75communicating with the interior of the casing 12 through one or moreslots or openings 76 and mounting within the cavity one or morecompressible tubes 77 which are inflated at appropriate pressure todampen pulsations.

The form of vane described above is preferred, but it also issusceptible to modification in the manner shown in FIGURES 3 to 7. Thus,as shown in FIGURE 3, one side plate 78 of the vane 37' is of generallyL-shaped cross-section, While the other side plate 79 is of somewhatthicker rectangular cross-section. The vane section 81 is interposedbetween the outer edges of the plates 78 and 79 which are forced apartby means of a series of bowed springs 82. The springs are located bymeans of the resilient sealing ring 83, which rests on the inturnedflange '84 on the plate 78 and engages the vane portion 79.

FIGURE 4 shows another form of vane 37 which includes the two side vaneplates 86 and 87 having inturned inner flanges 88 and 89 against whichthe sealing strip 90 rests. Bearing against the ring 90 between bowedsprings not shown but similar to the springs '82, are a series of coilsprings 91 which bear against the wall contacting vane section 92 andagainst a button or abutment 93 resting on the sealing strip 90. In thisform of the invention, the bowed springs force the vane sections 86 and87 apart while the coil spring 91 aids in maintaining engagement betweenthe vane portion 92 and the wall of the pump casing.

In FIGURE 5, the vane 37" is composed of five pieces including two widehelical vane plates 94 and 95, a contacting vane section 96, and a pairof twisted helical springs 97 and 98 extending lengthwise between theplates 94 and 95 to force the vane portions 94 and 95 apart and the vaneportion 96 outwardly. A similar twisted helical spring 100 is used asshown in FIGURE 6 to force the vane sections 101 and 102 against thewalls of the groove and the rotor and also to urge outwardly a resilientvane strip 103 which may be formed of rubber, neoprene or the like.

Instead of using metallic springs for maintaining the side vane sectionsin contact with the walls of the grooves in the rotor, as shown inFIGURE 7, a strip of resilient material such as rubber, neoprene or thelike, may be interposed between the side vane sections 105 and 106. Toposition the strip 104, one or both of the vane sections may be providedwith a groove 107. The strip 104 also seals the space between the vanesections 105 and 106 against radial inward or outward leakage. It willbe understood that all of the several different types of springs 43, 91and 104 can be used in a single vane to provide the desired leak-proofseal and zero clearance between the vane, rotor and easing wall.

All of the modified vanes shown in FIGURES 3 to 7 may be secured attheir opposite ends with respect to the 6 rotor in the manner of thevanes disclosed in FIGURES 1, 2 and 8.

Other changes in the size, proportions and the like of the pump orcompressor can be made without departing from the invention andaccordingly, the forms of the invention described above should beconsidered as illustrative and not as limiting the following claims.

I claim:

1. Pumps, compressors and the like comprising a casing having aninternal cylindrical wall, a drive shaft in said casing concentric withsaid wall, means in said casing supporting said drive shaft forrotation, an eccentric mounted on said shaft for rotation therewith, acylindrical rotor in said casing of less external diameter than saidcylindrical wall, means resiliently mounting said rotor on saideccentric for gyration in said casing and engagement with said wall,said resilient means urging said rotor against said wall, a generallyhelical groove in the exterior of said rotor, a helical vane fitting insaid groove and engaging said wall throughout substantially the entirelength of said vane, said groove being deeper than the width of the vaneto enable said rotor to move radially relative to said vane, meanspositioning opposite ends of said vane relative to said rotor to enablesaid relative radial movement between said vane and rotor, an inlet insaid casing adjacent one end of said vane and an outlet in said casingadjacent to the other end of said vane.

2. Pumps, compressors and the like as set forth in claim 1 in which saidvane comprises a pair of generally helical side plates disposed in saidgroove, a generally helical vane member disposed between said sideplates and resiliently engaging said wall, and resilient means betweensaid side plate urging them apart into sealing engagement with saidgroove.

3. Pumps, compressors and the like as set forth in claim 2, comprising aresilient sealing strip between said side plates adjacent to their inneredges, and an inturned flange on the inner edge of at least one of saidside plates for retaining said strip between said side plate.

4. Pumps, compressors and the like as set forth in claim 2 in which saidresilient means comprises metallic springs.

5. Pumps, compressors and the like as set forth in claim 2 in which saidresilient means comprises a plurality of bowed metallic spring plates.

6. Pumps, compressors and the like as set forth in claim 2 in which saidresilient means comprises at least one helical transversely twistedmetallic spring.

7. Pumps, compressors and the like as set forth in claim 1 in which saidrotor is in rolling engagement with said cylindrical wall and said meansfor positioning said vane relative to said rotor comprises a constantvelocity coupling for rotating said vane with said rotor and enablingradial movement of said rotor relative to said vane.

8. Pumps, compressors and the like as set forth in claim 7 comprising aslidable coupling connected to the other end of said vane and said rotorand disposed in and substantially sealing said groove adjacent to saidother end of said vane.

9. Pumps, compressors and the like as set forth in claim 1 comprisingcompressible pulsation absorbing means in said casing adjacent to saidoutlet port.

10. Pumps, compressors and the like as set forth in claim 1 comprisingmeans on said drive shaft for counterbalancing said rotor.

11. Pumps, compressors and the like as set forth in claim 1 comprisingmeans for introducing a. lubricant into said intake port to lubricatesaid cylindrical wall, rotor and vane.

12. Pumps, compressors and the like as set forth in claim 1 in whichsaid rotor is hollow and has an opening in at least one end thereof, andcomprising pressure relief means in said rotor extending from theexterior of said rotor to its interior adjacent to said outlet port forregulating the pressure between said rotor, vane and wall adjacent tosald outlet port.

13. Pumps, compressors and the like as set forth in claim 1 in whichsaid rotor is hollow and has an opening in at least one end thereof andcomprising vent means in the bottom of the groove in said rotor to theinterior of said rotor to vent fluid from said groove inwardly of saidvane.

14. Pumps, compressors and the like as set forth in claim 1 in whichsaid rotor is hollow and has an opening in at least one end thereof andcomprising vent means in the bottom of the groove in said rotor to theinterior of said rotor to vent fluid from said groove inwardly of saidvane and comprising pressure regulating means in said rotor extendingfrom the exterior of said rotor to its interior adjacent to said outletport for regulating the exsaid outlet port.

References Cited by the Examiner FOREIGN PATENTS 12/1924 Great Britain.5/1936 Great Britain.

MARK NEWMAN, Primary Examiner.

cess pressure between said rotor, vane and Wall adjacent 15 W. J.GOODLIN, Assistant Examiner.

1. PUMPS, COMPRESSORS AND THE LIKE COMPRISING A CASING HAVING ANINTERNAL CYLINDRICAL WALL, A DRIVE SHAFT IN SAID CASING CONCENTRIC WITHSAID WALL, MEANS IN SAID CASING SUPPORTING SAID DRIVE SHAFT FORROTATION, AN ECCENTRIC MOUNTED ON SAID SHAFT FOR ROTATION THEREWITH, ACYLINDRICAL ROTOR IN SAID CASING OF LESS EXTERNAL DIAMETER THAN SAIDCYLINDRICAL WALL, MEANS RESILIENTLY MOUNTING SAID ROTOR ON SAIDECCENTRIC FOR GYRATION IN SAID CASING SAID ENGAGEMENT WITH SAID WALL,SAID RESILIENT MEAND URGING SAID ROTOR AGAINST SAID WALL, A GENERALLYHELICAL GROOVE IN THE EXTERIOR OF SAID ROTOR, A HELICAL VANE FITTING INSAID GROOVE AND ENGAGING SAID WALL THROUGHOUT SUBSTANTIALLY THE ENTIRELENGTH OF SAID VANE, SAID GROOVE BEING DEEPER THAN THE WIDTH OF THE VANETO ENABLE SAID ROTOR TO MOVE RADIALLY RELATIVE TO SAID VANE, MEANSPOSITIONING OPPOSITE ENDS OF SAID VANE RELATIVE TO SAID ROTOR TO ENABLESAID RELATIVE